Window bag and method of producing same

ABSTRACT

A block-bottom or cross-bottom window bag having a graphic thereon is made by imprinting one side of a substrate web with a graphic, applying to substantially the entirety of that one side of the substrate web a thermally activatable laminating medium, punching a window opening through the substrate web in an area thereof not imprinted with the graphic, and, by thermal activation of the laminating medium, laminating onto substantially the entirety of the substrate web a transparent film thereby covering the window opening with the transparent film, and forming the block-bottom or cross-bottom bag from the laminated substrate web with the transparent film constituting the exterior of the bag.

BACKGROUND OF THE INVENTION

The invention relates to block-bottom or crossed-bottom bags that are closed with a transparent window film and that have a window punched from a substrate web and that act as so-called window bags using their interiors both for receiving and for presenting items packaged therein and that are printed with a graphic on the front side of the substrate web opposing the interior and furthermore relates to a generic method for producing a substrate web having a punched window that is closed with a transparent window film from which the generic window bags are produced, whereby the continuously fed substrate web is first printed with a graphic on its front side that forms the outside of the window bag and then the window is punched.

Block-bottom or crossed-bottom bags provided with a window that is closed by a transparent film, so-called window bags, and methods for producing them, are known. The front side of the substrate web that forms the outside of the bag is printed where necessary with a graphic using flexographic or rotogravure printing. Then the window is punched in a bag machine and then the transparent window film is glued to the inside of the substrate web that opposes the front side. This can occur with individual windowpane-shaped film pieces that are already pre-formed or the window film can be used continuously inline as a roller good during production. Finally, it is also possible to provide the entire inside of the bag with the window film behind the window. Due to the continuous production of the bags, a certain adhesive tolerance of approx. 2 to 3 mm must be maintained between the punch edge of the window and the edge of the window film. It is possible to provide numerous contours for the window to be punched. In any case, precise gluing is important in order to prevent parts of non-glued edges of the punched window from folding over during further processing, specifically during filling and sealing for a customer.

The object of the invention is to provide window bags and a method for producing them in which all types of contours for the punched window are possible without the risk that non-glued areas on the edge of the window will fold over during further processing.

SUMMARY OF THE INVENTION

This object is thus inventively attained in that the entire front side of the substrate web of the window bag is laminated with the window film or is attained using the following method steps: prior to punching the window, a laminating medium is applied to the complete surface of the front side of the substrate web that has already been printed; then, corresponding to the graphic, the window is punched from the substrate web; and finally the window film that forms the outside of the window bag is applied to its front side and over its entire width and is laminated using thermal activation of the laminating medium.

Thus, according to a first aspect of the invention, there is provided a block-bottom or cross-bottom window bag comprising a bag body comprised of a laminated web, the laminated web being comprised of a substrate web having a window opening therethrough and imprinted on one side thereof a graphic and a transparent film laminated onto substantially the entirety of the one side of the substrate and covering the window opening, wherein the one side of the laminated web comprises an exterior of the bag displaying the graphic and the other side of the laminated web comprises an exterior of the bag.

According to a second aspect of the invention, there is provided a method of producing a laminated web comprising a substrate web having a window opening therethrough and a graphic imprinted on one side thereof, and, laminated onto substantially the entirety of the one side thereof, a transparent film which covers the window opening, comprising imprinting one side of the substrate with a graphic, applying to substantially the entirety of that one side of the substrate web a thermally activatable laminating medium for adhering to the one side said transparent film to be subsequently laminated, punching a window opening through the substrate in an area thereof not imprinted with the graphic, and by thermal activation of the laminating medium, laminating onto substantially the entirety of the one side of the substrate and covering the window opening with the transparent film.

According to a third aspect of the invention, there is provided a method of producing block-bottom or cross-bottom window bags, comprising producing a laminated web by the method of the second aspect of the invention and forming the laminated web into block-bottom or cross-bottom bags so that the one side of the laminated web comprises an exterior of each of the bags displaying the graphic and the other side of the laminated web comprises an interior of each of the bags.

According to a fourth aspect of the invention, the substrate web is continuously fed and the feeding and the punching of the web are coordinated to effect the punching of each window opening through said substrate web in the areas thereof not imprinted with the graphic.

According to a fifth aspect of the invention, the punching is effected by a press, such as a die press, or a laminating or slitting machine.

According to a sixth aspect of the invention, the forming of the bags is effected by a bag machine or a form-fill-and seal-machine.

According to a seventh aspect of the invention, the laminated web is wound onto a reel.

According to an eighth aspect of the invention, the laminated web is unwound from the reel and the laminated web is formed into a block-bottom or cross-bottom window bag, such as by a bag machine or a form-fill and seal-machine.

According to a ninth aspect of the invention, the transparent film is oriented polypropylene.

According to an tenth aspect of the invention, the aforementioned one side of the substrate web is of paper.

According to an eleventh aspect of the invention, the substrate web with the laminating medium is laminated with more than one web of the transparent film so that the transparent film of the bag is of more than one layer.

In contrast to the known method, then, according to the teaching of the invention a laminating medium is applied to the complete surface of the front side of the substrate web, which has already been printed, prior to punching the window. Only after this is the window punched from the substrate web by cycle to match the graphic i.e., so that the substrate material removed by the punching out of the window does not include the graphic. Finally the window film that forms the outside of the window bag is then applied to its front side and across its entire width and is laminated using thermal activation of the laminating medium.

This method of production has the advantage that using it completely new window bags can be produced in which the window film applied to the front side of the substrate web forms the entire outside and thus a closed surface on which no parts of punch contours project, as is the case in the generic prior art, that could then fold over during further processing. In addition, there is the fact that the inside of the substrate web, the punch edge of the window, and the edge of the window film are completely securely joined to one another to the edge of the punched area. Furthermore, using the inventive method it is possible to produce e.g. block-bottom bags whose windows extend from the front side, to an extent around the corner into the side fold into its area. Such a configuration was not possible in the application of the known generic method for reasons of stability.

In one useful further development of the invention, the substrate web that is laminated with the window film can be wound on a reel as an intermediate product that is also new. This reel can then be provided with the intermediate product to customers, and it is then either processed in a simple bag machine with a punching device for the windows or is processed in a so-called form, fill, and seal machine.

One exemplary embodiment of the invention is described in greater detail in the following, with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates a window package as a block-bottom bag, and,

FIG. 2 is a section II-II in accordance with FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

The illustrated so-called window bag 5 is embodied as a block-bottom bag and its interior 6 both receives and displays the packaged items. In addition, the front side 13 of the substrate web, from which the window bag 5 is produced and which opposes the inside 12 that faces the interior 6 of the window bag 5, can be printed with a graphic.

The window bag 5 additionally has a window 10 that is punched from the substrate web and the closed punched edge 7 of which reaches across the one side edge 8 of the window bag 5 to the area of the side fold 9.

Prior to punching the window 10, the entire front side 13 of the substrate web has been coated with a laminating medium to which now—from outside—a transparent window film 11 is laminated over the complete surface such that the latter is securely joined to the substrate web to the circumferential punched edge 7.

FIG. 2 provides a sectional view of the exteriorly located transparent film 11 substrate web 14 for the window bag 5. 

1.-10. (canceled)
 11. A block-bottom or cross-bottom window bag comprising a bag body comprised of a laminated web, the laminated web being comprised of a substrate web having a window opening therethrough and imprinted on one side thereof a graphic and a transparent film laminated onto substantially the entirety of said one side of the substrate and covering the window opening, wherein said one side of the laminated web comprises an exterior of the bag displaying the graphic and another side of the laminated web comprises an exterior of the bag.
 12. Method of producing a laminated web comprising a substrate web having a window opening therethrough and a graphic imprinted on one side thereof, and, laminated onto substantially the entirety of said one side thereof, a transparent film which covers the window opening, comprising imprinting said one side of the substrate with a graphic, applying to substantially the entirety of said one side of the substrate web a thermally activatable laminating medium for adhering to said one side said transparent film to be subsequently laminated, punching a window opening through the substrate in an area thereof not imprinted with the graphic, and by thermal activation of the laminating medium, laminating onto substantially the entirety of said one side of the substrate and covering the window opening with said transparent film.
 13. A method of producing block-bottom or cross-bottom window bags, comprising producing a laminated web by the method of claim 11 and forming the laminated web into block-bottom or cross-bottom bags so that said one side of the laminated web comprises an exterior of each of the bags displaying the graphic and another side of the laminated web comprises an interior of each of the bags.
 14. Method according to claim 12 or 13, wherein the substrate web is continuously fed and the feeding and the punching of the web are coordinated to effect the punching of each window opening through said substrate web in the areas thereof not imprinted with the graphic.
 15. Method according to claim 12 or 13, wherein said punching is effected by a press or a laminating or slitting machine.
 16. Method according to claim 13, wherein the forming of the bags is effected by a bag machine or a form-fill-and seal-machine.
 17. Method according to claim 12, further comprising winding the laminated web onto a reel.
 18. A method of producing a block-bottom or cross-bottom bag, comprising producing a laminated web on a reel by the method of claim 17, unwinding the laminated web from the reel and forming the laminated web into a block-bottom or cross-bottom window bag.
 19. Method according to claim 18, wherein the forming of the bag is effected by a bag machine or a form-fill- and seal-machine.
 20. Method according to claim 11, 12 or 13, wherein said transparent film is comprised of oriented polypropylene.
 21. Method according to claim 12 or 13, wherein said one side of the substrate web is comprised of paper.
 22. Method according to claim 12 or 13, wherein the transparent film comprises a plurality of webs of transparent film. 